Non-volatile display cells have been developed. One such non-volatile display cell is shown in U.S. Pat. No. 4,309,083 for ELECTRODE FOR ELECTROLYTIC CELL PARTICULARLY FOR ELECTROLYTIC DISPLAY CELLS AND PROCESS OF MANUFACTURE and in U.S. Pat. No. 4,306,755 for ELECTROLYTIC DISPLAY CELL AND CONTROL THEREOF. These non-volatile display cells are of the plating variety and have been suggested as being useful in seven segment displays as for example for watches and clocks.
In display cells of the above type, an electrolytic solution such as a metal salt in aqueous solution is disposed between an electrode or segment and the ground plane. Leads are connected to the ground plane and electrode and are brought out to a connector. The display electrode or segment may be a tin oxide coating, such as a nesa coating, deposited on a glass support substrate. In a like manner, the ground plane may also be a tin oxide coating, such as a nesa coating, deposited on a glass substrate. The various leads may be fabricated from tin oxide or other suitable material and encapsulated in an insulating material such as silicone dioxide to prevent interaction with the electrolytic solution. The structure and operation of the display as associated with the write and erase operation only is disclosed in the above noted U.S. Patents, namely U.S. Pat. No. 4,309,083 for ELECTRODE FOR ELECTROLYTIC CELL PARTICULARLY FOR ELECTROLYTIC DISPLAY CELLS AND PROCESS OF MANUFACTURE and in U.S. Pat. No. 4,306,775 for ELECTROLYTIC DISPLAY CELL AND CONTROL THEREFORE. The disclosures of these two patents are hereby incorporated by reference into the disclosure of this application. It should be noted that the system disclosed in U.S. Pat. No. 4,306,775 employs an additional electrode for controlling the writing and erase current associated with plating and deplating the display segment.
U.S. Pat. No. 4,345,820 for VISUAL DISPLAY APPARATUS FOR ELECTRICAL SIGNALS RECORDED ON A MAGNETIC MEDIUM discloses an apparatus for the visual display of electrical signals recorded on a magnetic medium or support in the form of a magnifying glass which is a plate or sheet of transparent material in which there is a dimple closed by a membrane. The volume of a dimple containing a developing film sensitive to the magnetic field of a recording medium dispersion in a liquid. Under action of a magnetic field, the ferrite particles are displaced and give an image of the magnetic state of the medium.